--- a/PNGReader.st	Fri Jun 01 13:10:23 2018 +0200
+++ b/PNGReader.st	Sat Jun 02 07:09:39 2018 +0200
@@ -258,20 +258,20 @@
     samplesPerPixel == 2 ifTrue:[
         photometric == #blackIs0 ifTrue:[
             depth == 16 ifTrue:[
-                "/ force to r8+g8+b8+a8
+                "/ force grey8+a8 into red8+green8+blue8+a8
                 forceRGB := true. 
                 depthImage := 32.
                 bytesPerScanlineOut := width * 4.
                 bitsPerSampleOut := #[8 8 8 8].
             ] ifFalse:[
                 depth == 32 ifTrue:[
-                    "/ force to r8+g8+b8+a8
+                    "/ force grey16+a16 into red8+green8+blue8+a8
                     forceRGB := true. 
                     depthImage := 32.
                     bytesPerScanlineOut := width * 4.
                     bitsPerSampleOut := #[8 8 8 8].
                 ] ifFalse:[
-                    self halt.
+                    self error:'unsupported grayscale image depth'.
                 ].    
             ].    
         ].    
@@ -314,6 +314,7 @@
     "
 
     "Modified: / 17-09-2017 / 15:30:45 / cg"
+    "Modified (format): / 02-06-2018 / 06:55:59 / Claus Gittinger"
 ! !
 
 !PNGReader methodsFor:'reading-private'!
@@ -393,7 +394,8 @@
     (inStream nextBytes:4 into:type) ~~ 4 ifTrue:[^ false].
 
     Verbose == true ifTrue:[
-        'len: ' infoPrint. len infoPrint. ' type: ' infoPrint. type infoPrintCR.
+        'PNGReader: chunk: ' infoPrint. type infoPrint.
+        ' len: ' infoPrint. len infoPrintCR.
     ].
 
     type = 'IEND' ifTrue:[^ false].
@@ -403,8 +405,8 @@
     crc := inStream nextInt32MSB:true.  "/ ignored - for now
     ^ true
 
-    "Created: 21.6.1996 / 21:09:36 / cg"
-    "Modified: 21.6.1996 / 21:20:26 / cg"
+    "Created: / 21-06-1996 / 21:09:36 / cg"
+    "Modified: / 02-06-2018 / 06:42:58 / Claus Gittinger"
 !
 
 getIHDRChunk
@@ -656,6 +658,7 @@
 
     "Created: / 21-06-1996 / 21:10:37 / cg"
     "Modified: / 11-04-2017 / 17:04:12 / cg"
+    "Modified: / 02-06-2018 / 06:43:03 / Claus Gittinger"
 !
 
 processEXEXChunkLen:len    
@@ -773,8 +776,12 @@
 !
 
 processInterlacedDATA:len
+    'PNGReader: skip unsupported interlaced data' infoPrintCR.
+    
     inStream skip:len.
     ^ true
+
+    "Modified: / 02-06-2018 / 06:40:22 / Claus Gittinger"
 !
 
 processInterlacedGlobalDATA
@@ -792,6 +799,10 @@
       h        "{ Class: SmallInteger }"
     |
 
+    Verbose == true ifTrue:[
+        'PNGReader: process interlaced global data' infoPrintCR.
+    ].
+    
     interlaceMode == 1 ifFalse: [
         self error:'unsupported interlaced mode'.
         ^ self
@@ -836,6 +847,7 @@
     zlibReader atEnd ifFalse:[self error:'Unexpected data'].
 
     "Modified: / 03-05-2011 / 12:03:33 / cg"
+    "Modified: / 02-06-2018 / 06:43:26 / Claus Gittinger"
 !
 
 processNIVIChunkLen:len    
@@ -877,6 +889,10 @@
 processNonInterlacedGlobalDATA
     | "data n" zlibReader filter temp "filtersSeen" i|
 
+    Verbose == true ifTrue:[
+        'PNGReader: process non-interlaced global data' infoPrintCR.
+    ].
+
     "/ filtersSeen := Set new.
 
 "/    data := ByteArray new:(self bytesPerRow * height)+1000.
@@ -901,9 +917,12 @@
             self filterScanline: filter count: bytesPerScanline 
         ].
 
-        i := y * bytesPerScanline.
-        data replaceFrom:i+1 to:(i+bytesPerScanline) with:thisScanline startingAt:1.
-
+        forceRGB ifTrue:[
+            self copyPixels:y at:0 by:1.
+        ] ifFalse:[        
+            i := y * bytesPerScanline.
+            data replaceFrom:i+1 to:(i+bytesPerScanline) with:thisScanline startingAt:1.
+        ].
         temp := prevScanline.
         prevScanline := thisScanline.
         thisScanline := temp
@@ -911,6 +930,7 @@
 
     "Modified: / 16-02-2017 / 16:45:52 / cg"
     "Modified (format): / 23-08-2017 / 17:05:01 / cg"
+    "Modified: / 02-06-2018 / 07:05:06 / Claus Gittinger"
 !
 
 processPHYSChunkLen:len
@@ -1112,8 +1132,6 @@
      && __isSmallInteger(count)) {
         unsigned char *__thisScanline = __byteArrayVal(__INST(thisScanline));
         unsigned int __sz_this = __byteArraySize(__INST(thisScanline));
-        unsigned char *__prevScanline = __byteArrayVal(__INST(prevScanline));
-        unsigned int __sz_prev = __byteArraySize(__INST(prevScanline));
         INT __count = __intVal(count);
         INT __delta = __intVal(__INST(depth)) / 8;
         int __i;
@@ -1130,6 +1148,8 @@
     delta+1 to:count do:[:i|
         thisScanline at:i put:(((thisScanline at:i)+ (thisScanline at:i-delta)) bitAnd:255) 
     ]
+
+    "Modified: / 02-06-2018 / 06:50:57 / Claus Gittinger"
 !
 
 filterNone: count
@@ -1523,7 +1543,7 @@
             dstIndex := (y * (width * 4)) + (startX*4) + 1.
 
             1 to:nPixels do:[:n |
-                pix := thisScanline unsignedInt16At:srcIndex.
+                pix := thisScanline unsignedInt16At:srcIndex MSB:true.
                 alpha := pix bitAnd:16rFF.
                 gray := (pix rightShift:8) bitAnd:16rFF.
                 "/ put r-g-b-a
@@ -1544,7 +1564,7 @@
             dstIndex := (y * (width * 4)) + (startX*4) + 1.
 
             1 to:nPixels do:[:n |
-                pix := thisScanline unsignedInt32At:srcIndex.
+                pix := thisScanline unsignedInt32At:srcIndex MSB:true.
                 
                 alpha := pix bitAnd:16rFFFF.
                 gray := (pix rightShift:16) bitAnd:16rFFFF.
@@ -1568,6 +1588,7 @@
 
     "Created: / 17-09-2017 / 14:20:24 / cg"
     "Modified: / 17-09-2017 / 15:28:38 / cg"
+    "Modified: / 02-06-2018 / 07:08:15 / Claus Gittinger"
 !
 
 copyPixelsIndexed:y at:startX by:incX